At present, Evolved Universal Terrestrial Radio Access (hereinafter, referred to as “EUTRA”) for the purpose of increasing the communication speed by introducing part of a technique having been discussed for the fourth generation into the third generation frequency band is discussed by the standardization group 3GPP (3rd Generation Partnership Project) (for example, refer to non-patent document 1).
It has been determined that the OFDMA (Orthogonal Frequency Division Multiplexing Access) scheme that is robust against multi-path interference and suitable for high-speed transmission is adopted as a communication scheme for EUTRA. In addition, in order to improve the uplink throughput of a mobile station on a cell edge and to increase the capacity of the whole cell, the introduction of a technique, called an interference coordination, for the purpose of suppressing inter-cell interference in an uplink transmission is widely discussed (for example, refer to non-patent document 1).
As an interference coordination, a plurality of methods has been proposed. As one of them, a method has been proposed, in which the frequency band that can be used in a system is divided into several parts, mobile stations are divided into several groups based on the transmission power, downlink received quality, etc., each group is associated with a divided frequency band, and a mobile station makes a transmission only in a corresponding frequency band (for example, refer to non-patent document 2). Non-patent document 2 has introduced a method for improving the throughput of transmission data without increasing an amount of interference between uplink cells by setting higher target quality of base station reception power in the corresponding frequency band as the distance between the mobile station and the base station becomes smaller.
On the other hand, another method has been proposed, in which the amount of interference between uplink cells is suppressed by only the adjustment of transmission power without division of a frequency band (for example, refer to non-patent document 3 and non-patent document 4). Non-patent document 3 has introduced a transmission power control method for suppressing inter-cell interference by taking into consideration interference that affects neighboring cells in addition to interference given by a path-loss within cell in the serving area and neighboring cells. Non-patent document 4 has introduced a method, in which an amount of interference given by neighboring cells is measured for each cell and when the amount of interference given exceeds a fixed threshold value, a report is made using a load indicator or individual mobile stations are notified and a mobile station that has received the load indicator reduces transmission power in order to reduce interference.
Non-patent document 1: 3GPP TR (Technical Report) 25.814, V1.5.0 (2006-5), Physical Layer Aspects for Evolved UTRA. http//www.3gpp.org/ftp/Specs/html-info/25814.htm
Non-patent document 2: Nokia, “Uplink inter cell interference mitigation and text proposal”, 3GPP TSG RAN WG1 Meeting #44, Denver, USA, 13-17 Feb., 2006, R1-060298 Non-patent document 3: Texas Instruments, “Uplink Power Control for EUTRA: Optimizing the Trade-off between Cell-Edge and Cell-Average Throughputs”, 3GPP TSG RAN WG1 Meeting #47, Riga, Latvia, 6-10, Nov., 2006, R1-063231 Non-patent document 4: NTT DoCoMo, et al, “Transmission Power Control in E-UTRA Uplink”, 3GPP TSG RAN WG1 Meeting #47, Riga, Latvia, 6-10, Nov., 2006, R1-063316TBD